Incendiary composition containing an aluminum alkyl compound

ABSTRACT

Aluminum trialkyls and aluminum alkyl hydrides are thickened with a paraffin wax to form gellike incendiary compositions. Additionally, the incendiary may contain diluents which are compatible with aluminum alkyls such as hydrocarbons, finely divided metals and certain organometallic compounds. These incendiaries ignite spontaneously upon contact with air or water and, therefore, are useful in flamethrowers, firebombs, fire rockets, and other flame-producing weapons.

United States Patent William Burns Warren, Mich. 614,523

Jan. 30, 1967 Jan. 11, 1972 Ethyl Corporation New York, N.Y.

Inventor Appl. No. Filed Patented Assignee INCENDIARY COMPOSITION CONTAINING AN ALUMINUM ALKYL COMPOUND 7 Claims, No Drawings U.S. Cl 44/7, 149/18, 149/87 Int. Cl C101 7/02 Field of Search 44/7; 149/87, 19,18

[56] References Cited UNITED STATES PATENTS 2,765,329 10/1956 Lindsey, Jr. 149/87 X 3,167,525 1/1965 Thomas 149/87 X FOREIGN PATENTS 637,682 5/1950 Great Britain 149/87 Primary Examiner Leland A. Sebastian Attorney-Donald L. Johnson ABSTRACT: Aluminum trialkyls and aluminum alkyl hydrides are thickened with a paraffin wax to form gellike incendiary compositions. Additionally, the incendiary may contain diluents which are compatible with aluminum alkyls such as hydrocarbons, finely divided metals and certain organomctallic compounds. These incendiaries ignite spontaneously upon contact with air or water and, therefore, are useful in flamethrower-s, firebombs, fire rockets, and other flameproducing weapons.

IN CENDIARY COMPOSITION CONTAINING AN ALUMINUM ALKYL COMPOUND BACKGROUND OF THE INVENTION This invention relates to incendiary compositions and to methods of dispersing incendiary compositions thereby producing an effective conflagration.

Incendiary compositions such as contained in firebombs, fire rockets, or ejected from flamethrowers, now generally in use, are ignited by means of a fuse, a spark, or some other external mechanism. The ignition process may be commenced when the incendiary is propelled or released from the source, or the ignition mechanism may be actuated when the projectile strikes the target. While these ignition techniques have achieved a degree of success, they are subject to malfunction and the incendiary composition may not ignite and thus is totally ineffective.

Current incendiary compositions consist mainly of gelled or thickened gasoline. While this material is usually quite flammable, it must be independently ignited and often does not burn completely. Upon striking the target, only that portion remaining in the area of ignition will burn. Because of its relatively high volatility, the unburned gasoline will quickly vaporize and, thus, preclude any possibility of future ignition. Moreover, the burning of these compositions is not very intense and may be extinguished or otherwise rendered ineffective for the purpose intended.

Another shortcoming with current incendiary compositions, and particularly those ejected from equipment such as a flamethrower, is the extremely short range. Even when ejected under high pressure and, therefore, at high velocities, the incendiary composition, ignited as it leaves the flamethrower, is completely burned within a relatively short range from the source. Thus, the use of this type equipment is limited to extremely short range applications.

SUMMARY OF THE INVENTION A self-igniting incendiary composition having a gellike consistency is obtained by thickening from about 75 to about 94 weight percent of aluminum alkyls and from about 6 to 25 weight percent of the paraffin wax thickening agent. The composition may also contain from O to about 20 weight percent of a diluent.

DESCRIPTION OF THE INVENTION The incendiary compositions of this invention are self-igniting incendiaries containing varying percentages of aluminum compounds thickened with a paraffin wax. More specifically, the aluminum compounds contemplated are the alkyl aluminums and alkyl aluminum hydrides, hereinafter referred to simply as aluminum alkyls. These compounds have the formula:

where R is an alkyl group containing from one to four carbon atoms, and x is an integer ranging from 1 to 3. In a preferred embodiment, R is a lower alkyl group containing up to three carbon atoms and x is equal to 2 or 3. These materials are more reactive than the higher alkyls and, thus, assure maximum effectiveness. The most preferred embodiment comprises a composition wherein the aluminum alkyl component consists of from 90 to 100 percent triethylaluminum and from to 10 percent diethylaluminum hydride. This composition is preferred because it is of intermediate reactivity, volatility, and stability and is relatively economical to manufacture.

The compounds which are useful in the incendiary compositions of this invention include trimethylaluminum, dimethylaluminum hydride, methylaluminum dihydride, triethylaluminum, diethylaluminum hydride, ethylaluminum dihydride, tripropylaluminum, dipropylaluminum hydride, propylaluminum dihydride, tributylaluminum, dibutylaluminum hydride, butylaluminum dihydride, triisobutylaluminum, diisobutylaluminum hydride, isobutylaluminum dihydride. The higher alkyl aluminum compounds including amyl and hexyl aluminums and the aromatic aluminum compounds such as the phenyl, tolyl, xylyl, etc. aluminum compounds can also be used in the compositions of this invention, especially as diluents to impart certain characteristics to the lower aluminum alkyl mixture.

The paraffin waxes which are useful in the incendiary compositions of this invention include those which have a melting point ranging from about 135 F. to about 2l4 F. This includes commercially available paraffin waxes that have a melting point of l35l37 F.; Extra Hard Paraffin Wax melting at Il75 F. (available from Sargent Company); Code 700 Wax melting at about 18] .5 F and Synthetic Coal Tar Wax melting at about 214 F. (grated, white wax); the last three being available from the Kalamazoo Paraffine Company.

This invention provides thickened or gelled incendiary compositions. Such compositions comprise from about to 94 weight percent aluminum alkyls and from about 6 to 25 weight percent of the paraffin wax thickening agent. More preferably, these compositions comprise from about to 91 weight percent of aluminum alkyls and from about 9 to 20 weight percent of the thickening agent. The incendiary composition may also contain up to 20 weight percent of a diluent as described below.

In another aspect of this invention is provided a method of producing a conflagration which comprises dispersing a diluted or thickened incendiary composition as described above in or over a target area.

The aluminum alkyls are ideally suited as incendiary materials, for upon contact with air, they spontaneously ignite and burn with an intense flame. Therefore, the igniting mechanism, which is required with prior art incendiaries. is eliminated. Concentrated aluminum alkyls also react with water to give a violent and sometimes explosive reaction. The compounds also react with other compounds containing active hydrogen such as alcohols, amines, organic and inorganic acids, and to some extent with materials such as paper and cloth. Therefore, the application of the incendiary compositions of this invention is not restricted to an air media but can be used in a wide variety of applications with maximum reliability and effectiveness.

The thickened or gelled aluminum alkyl compositions have much lower volatility than unthickened materials. Since the rate of evaporation of the incendiary is decreased, the thickened compositions may be propelled over longer distances than the unthickened compositions when used in applications such as flamethrowers. A further advantage of thickened aluminum alkyls is that such materials are able to transfer heat to the target much better than the unthickened material.

Depending upon the specific application, the incendiary compositions may be in different forms. The consistency of the mixture may vary from a mobile fluid to a highly thickened gel. The consistency is varied by including up to about 25 percent ofthe thickener and, if desired, a diluent. Amounts of the diluents and thickeners in much greater concentration than the above limit impairs the ignition properties of the incendiary compositions.

The addition of diluents to the thickened aluminum alkyls serves a variety of purposes. By selection of the proper diluent, an incendiary composition may be obtained that has optimum properties with respect to density, volatility, reactivity, ignition delay characteristics, etc., and in many cases provides a more economical mixture. Broadly, any material which is compatible and does not react with aluminum alkyls or the thickener may be used as a diluent. It is preferable that the material to be used as a diluent is itself capable of combustion when heated to its kindling temperature. The materials useable as diluents include hydrocarbons, finely divided metals, and organometallic compounds, preferably those not containing reactive functional groups, and not containing oxygen or reactive hydrogen. More specifically, petroleum derived hydrocarbons such as gasoline, kerosene, tar, asphalt, petroleum jelly, heavy lubricating oil, mineral oil, etc. are useable.

Metals such as iron, magnesium, aluminum, zinc, boron, lithium, sodium, etc. in a finely divided state or their organic compounds such as diethylzinc, tributyl borine, may be'used.

Other organometallic compounds may also be used, especially those containing a cyclomatic radical such as dicyclopentadienyl iron, methylcyclopentadienyl manganese tricarbonyL' dicyclopentadienyl manganese, etc. Other metallic compounds may be included in the compositions, especially sodium hydride, sodium aluminum hydride, sodium borohydride, lithium borohydride, or any of the sodium alkali metal hydrides, aluminum hydrides, or borohydrides. These normally solid compounds are partially soluble in the aluminum alkyls. The higher alkyl and aromatic compounds of aluminum such as tripentylaluminum, trihexylaluminum, triphenylalu-- minum, etc., may also be'included as diluents. These'materials' are much less. reactive than the lower alkyls and, thus, may be employed toobtain a less reactive, more controllable incendiary composition. The above-mentioned diluents may be emspheres propelled from devices such as a compressed-gas gun .or mortar which could launch a package of such capsules.

Aluminum alkyl compositions are also ideally suited as flamethrower fuels. The compositions of this invention are a tailor-made" com osition is available with various i nition delay periods. ln this manner, the effective range of instru' self-igniting, producing a higher flame temperature than nor- -mally'used materials such as gelled gasoline and, in addition,

cause both chemical and thermal injuries to personnel. These compositions are-also amenable to nonmilitary applications such'as flares either of the stationary type or discharged from a hand pistol as aerial flares, etc.

An example of the incendiary bomb provided by this invention comprises a sheet steel shell having a ballistic configuration tapering down to a forward nose section which is con structed of heavy steel to facilitate penetration into the intended target. The rear portion ofthe shell terminates in a tail assembly which includes an opening through which theshell is filled with the incendiary composition, and fins to stabilize the flight of the bomb and, thus, improve accuracy. Appropriate means such as a threaded plug are used to seal the opening after filling. The bomb may be jettisoned from an aircraft singly or it may be in a cluster from which individual bombs are released during the descent. The above-described incendiary bomb is designed to fracture due to its own momentum when it strikes the target, thereby releasing its content. Alter natively, the bomb may be equipped with any of the wellknown types of bursting charges for fragmenting the bomb shell and thereby forcefully expelling the incendiary composition. A fuse designed to function instantaneously upon impact or with a delayed action is incorporated into the nose section to ignite a small charge of explosive material such as gunpowder also contained therein. The igniting mechanism may also be designed to tire while the bomb is in flight prior to striking a target.

Many benefits accrue from the use of the incendiary compositions of this invention which were heretofore not obtainable. One important advantage is that the compositions are selfigniting when exposed to air. Accordingly, the independent ignition mechanism of current incendiaries is obviated, thereby precluding any failure of the ignition mechanism.

Another important advantage of this invention is that upon exposure to air, there is a certain delay period before self-ignition takes place. The ignition delay period varies with different aluminum alkyl compounds. For example, the ignition delay period for trimethylaluminum is much shorter than for a higher alkyl such as tributylaluminum. Moreover, the ignition delay period may be altered somewhat by altering the amounts of the paraffin wax thickening agent and of the diluent. Thus,

. mentalities such as flamethrowers can be increased, and only a part of the fuel will be burned before reaching the intended target.

Another advantage inusing the incendiaries of this inven' tion isthat they are less volatile than currently used materials for this purpose-The aluminum alkyls will not evaporate as readily as gasoline and. thus, the material willburn on the surface of the target, thereby providing maximum effectiveness.

The aluminum alkyls burn vigorously with an extremely hot flame. and are, therefore, much more difficult to extinguish than conventional incendiaries. These incendiaries also burn with a cleaiterflame, with a minimum of smoke, thereby making it difficult to locate and extinguish the flame.

The following examples illustrate the novel incendiary compositions of this invention and the methods of using said compositions. All parts are by weight unless otherwise indicated.

EXAMPLE 1 I To a vessel placed in a nitrogen atmosphere were added 100 parts oftriethylaluminum and 6 parts. of Synthetic Coal Tar Wax melting at about 214 F. (grated, white wax) supplied by the Kalamazoo Paraffine Company. Afterheating the mixture to about 120 C., the contents were thoroughly mixed. The

7 resulting incendiary composition had a consistency of light slush.

When this example was repeated employing 9 parts of said Synthetic Coal TarWax, a somewhat heavier slushy material was obtained.

Similar results are obtained when in the above example a mixture of triethylaluminum and diethylaluminum hydride is employedin place of triethylaluminum. I

When Extra Hard Paraffin Wax, melting at l-l F., or

PM Yellow Wax, meltingat l205- F., are employed in the above example, comparable resultsare obtained.

EXAMPLE 2 Following the procedure of example 1, 25 parts of'paraffin wax, melting at l35l37 F. was mixedwith parts of triethylaluminum. The resulting gellike material was introduced into a flamethrower. The flamethrower was then fired under the following conditions: pressure 300 p.s.i.g.; elevation +5; outside temperature 41 F.; wind velocity 5 --l0 m.p.h. A 40-yard rod of flame was obtained which exhibited some breakup.

Similar results are obtained when trimethylaluminum, triisobutylaluminum, and a mixture of triethylaluminum and trimethylaluminum are employed in example 2 in place of triethylaluminum.

EXAMPLE 3 Following the procedure of example 1, 25 parts of Code 700 Wax melting at 1815' F. was mixed with 100 parts of triethylaluminum. A flamethrower was filled with the resulting composition and fired under the same conditions as specified in example 2 above. A 50-yard rod of flame was obtained. Satisfactory results are also obtained when Code 700 wax is employed in the amount of9 parts, 15 parts, and 20 parts per 100 parts of aluminum alkyl.

EXAMPLE 4 Following the procedure described in example 1, 15 parts of paraffin wax melting at l35-l 37 F. was mixed with 100 parts of triethylaluminum. A flame projector filled with the resulting composition was fired under the following conditions: pressure 300 p.s.i.g.; elevation +5"; outside temperature 68 F.; wind velocity 8 -l2 m.p.h. gusts. A 30-yard flame projection was obtained.

A similar result is obtained when trimethylaluminum is substituted for triethylaluminum in the amounts of 9 parts and 20 parts per 100 parts of the aluminum alkyl.

EXAMPLE 5 The same composition as in example 4 is prepared, but additionally, 20 parts of powdered lithium-aluminum alloy is added as a diluent. The alloy is composed of about weight percent of lithium and 85 weight percent of aluminum. The resulting composition, which has an even lower volatility than the thickened incendiary without the alloy, is then used in a flamethrower.

Similar compositions are obtained when diluents such as mineral oil, powdered iron, sodium, aluminum, and ferrocene are employed in the above example in place of the lithium-aluminum alloy.

in addition to the above specific embodiments, many other applications of my compositions and articles of manufacture will be obvious to those skilled in the art. Besides other miscellaneous applications such as booby traps and clandestine devices, the compositions of this invention may be used in landmines, or rocket projectiles, and fire starters in general.

The aluminum alkyls are well-known compounds. Methods for their preparation can be found in any standard texts including Organometallic Compounds," by G. E. Coates, 1960, John Wiley and Sons, Inc., New YOrk, New York; Organic Chemistry" by P. Karrer, 1950, Elsivier Publishing Company. New York, New York, etc.

Having fully described the novel compositions of this invention and the methods of preparing and using same, it is desired that this invention be limited only within the lawful scope of the appended claims.

I claim:

1. A thickened incendiary composition having a gellike consistency comprising from about 55 to about 84 weight percent ofan aluminum compound having the formula AlR H wherein R is an alkyl group and x is an integer ranging from 1 to 3; and from about 6 to about 25 weight percent of a paraffin wax gelling agent, and 0 to about 20 weight percent of a diluent.

2. The composition of claim 1 wherein said paraffin wax gelling agent has a melting point in the range of from about 135 to about 214 F.

3. The composition of claim 1 additionally containing up to about 20 weight percent of a diluent.

4. The composition of claim 1 wherein said aluminum compound is triethylaluminum.

5. The composition of claim 1 wherein said aluminum compound is a mixture of triethylaluminum and diethylaluminum hydride.

6. A composition of claim 1 wherein said aluminum compound is an alkyl aluminum hydride having one to two hydrogen atoms bonded to the aluminum atom.

7. A composition ofclaim 1 consisting essentially of about 15 parts by weight of paraffin wax about 100 parts by weight oftriethylaluminum, and

about 20 parts by weight of a powdered lithium-aluminum alloy, said alloy being composed of about 15 weight percent lithium and about weight percent aluminum. 

2. The composition of claim 1 wherein said paraffin wax gelling agent has a melting point in the range of from about 135* to about 214* F.
 3. The composition of claim 1 additionally containing up to about 20 weight percent of a diluent.
 4. The composition of claim 1 wherein said aluminum compound is triethylaluminum.
 5. The composition of claim 1 wherein said aluminum compound is a mixture of triethylaluminum and diethylaluminum hydride.
 6. A composition of claim 1 wherein said aluminum compound is an alkyl alUminum hydride having one to two hydrogen atoms bonded to the aluminum atom.
 7. A composition of claim 1 consisting essentially of about 15 parts by weight of paraffin wax about 100 parts by weight of triethylaluminum, and about 20 parts by weight of a powdered lithium-aluminum alloy, said alloy being composed of about 15 weight percent lithium and about 85 weight percent aluminum. 